Method and apparatus for managing user equipment history information in wireless communication network

ABSTRACT

A method and an apparatus are provided in a wireless communication system. The method includes generating mobility history information upon entering an evolved universal mobile telecommunications system (UMTS) radio access network (E-UTRAN) from another radio access technology (RAT), the mobility history information including information on a time duration for which the terminal stayed outside of the E-UTRAN; receiving, from a base station, a request for the mobility history information; and transmitting the mobility history information to the base station, in response to the request.

PRIORITY

This application is a Continuation Application of U.S. application Ser.No. 14/843,264, which was filed in the U.S. Patent and Trademark Office(USPTO) on Sep. 2, 2015, which is a Continuation Application of U.S.application Ser. No. 12/769,126, which was filed in the USPTO on Apr.28, 2010 and issued as U.S. Pat. No. 9,332,420 on May 3, 2016, andclaims priority to Koran Application Serial No, 10-2009-0037205, whichwas filed with the Korean Intellectual Property Office on Apr. 28, 2009,the entire content of each of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a wireless communication network, andmore particularly, to a method and an apparatus for managing UserEquipment (UE) history information in order to improve performance ofthe wireless communication network.

2. Description of the Related Art

Generally, a Universal Mobile Telecommunications System (UMTS) is athird generation (3G) mobile communication system that uses WidebandCode Division Multiple Access (WCDMA) based on Global System for Mobilecommunications (GSM) and General Packet Radio Services (CPRS). A thirdGeneration Partnership Project (3GPP) for standardization of the UMTShas suggested an Evolved Packet System (EPS) of the UMTS similar to theLong Term Evolution (LTE) system. In this case, the LTE system is atechnology for implementing high-speed packet based communication.

In the EPS, while a source base station is downloading source data, ahandover of a User Equipment (UE) can occur from the source base stationto a target base station. At this time, the source base station forwardsthe source data to the target base station. Further, the target basestation downloads the source data and next followed target data. In thiscase, the source base station records UE history information as a UEContext. Upon handover, the source base station transfers the UE historyinformation to the target base station.

The UE history information may include cell ID, cell type (large, small,etc.), a time served from a cell, and information on a plurality ofcells with information of a recent serving cell. The UE historyinformation is used to prevent a ping-pong handover of a UE from atarget cell (a continuous handover of the UE between two base stationswithin a short time) and for a radio resource allocation algorithm tothe UE after estimation of a moving speed of the UE. However, the UEdoes not process the UE history information even though the serving basestation creates it. When the UE firstly accesses the serving basestation, because the UE history information is not created, the servingbase station cannot use the UE history information.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above problems, andprovides a method for managing UE history information in a wirelesscommunication network that collects and provides its history informationby an UE operating in an idle mode to the wireless communicationnetwork, thereby providing an efficient data transmission environment tothe UE and providing valid information on an operation of a wirelesscommunication system to the wireless communication network.

In accordance with an aspect of the present invention, a method isprovided by a terminal in a wireless communication system. The methodincludes generating mobility history information upon entering anevolved universal mobile telecommunications system (UMTS) radio accessnetwork (E-UTRAN) from another radio access technology (RAT), themobility history information including information on a time durationfor which the terminal stayed outside of the E-UTRAN; receiving, from abase station, a request for the mobility history information; andtransmitting the mobility history information to the base station, inresponse to the request.

In a method for managing UE history information in a wirelesscommunication network accordance with the present invention, a UEtransmits its UE history information to a serving base station, so thatthe serving base station can provide an efficient data transmissionenvironment to the UE based on the UE history information. Further, theUE transmits its UE history information to an O&M (Operating andManagement) server or a core network entity of a wireless communicationnetwork, so that a network operator can use the UE history informationfor managing the wireless communication network.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features and advantages of the present invention will bemore apparent from the following detailed description in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a diagram illustrating a configuration of a wirelesscommunication network according to an embodiment of the presentinvention;

FIG. 2 is a sequence diagram illustrating a method for transmitting UEhistory information from a source base station to a target base stationat the time of a handover between macro base stations according to anexemplary embodiment of the present invention;

FIG. 3 is a diagram illustrating history information recorded by a UEoperating in an idle mode according to an embodiment of the presentinvention;

FIG. 4 is a diagram illustrating a procedure of recording UE historyinformation by a UE operating in an idle mode according to an embodimentof the present invention;

FIG. 5 is a sequence diagram illustrating a procedure of transmittingidle mode UE history information to a base station by a UE in an idlemode according to an embodiment of the present invention;

FIG. 6 is a flow chart illustrating an operation of a UE according to anembodiment of the present invention; and

FIG. 7 is a block diagram illustrating an internal configuration of a UEaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention are described with reference to theaccompanying drawings in detail. The same reference numbers are usedthroughout the drawings to refer to the same or like parts. Detaileddescriptions of well-known functions and structures incorporated hereinmay be omitted to avoid obscuring the subject matter of the presentinvention.

First, a configuration of a wireless communication network is described.The wireless communication network according to an embodiment of thepresent invention is configured based on a cellular system.

FIG. 1 is a diagram illustrating a configuration of a wirelesscommunication network according to an embodiment of the presentinvention.

Referring to FIG. 1, the wireless communication network according to anembodiment of the present invention includes a User Equipment (UE) 101,an Evolved UMTS Radio Access Network (E-UTRAN) 102, a MobilityManagement Entity (MME) 103, a Serving GateWay (SGW) 104, a Packet datanetwork GateWay (PGW) 105, a Packet Data Network 106, and an OperatorNetwork 107. The user equipment 101 may be fixed or mobile.

The E-UTRAN 102 accesses the UE 101 through a wireless channel. TheE-UTRAN 102 is composed of a plurality of cells. The E-UTRAN 102includes a plurality of evolved base stations, or Node Bs (eNBs) forcontrolling respective cells. The evolved base stations eNBs may beconnected to each other through an X2 interface. The evolved basestations (eNBs) execute a radio bearer control function, a radioadmission control function, a connection mobility control function, anda Radio Resource Management (RRM) function such as dynamic resourceallocation to the UE 101. Further, the evolved base stations eNBsexecute an Internet is Protocol (IP) header compression and dataencryption function, a data routing function, a scheduling andtransmitting function of a paging message, a scheduling and transmittingfunction of broadcast information, a measurement function for mobilityand scheduling, and a measurement report set function. Namely, theevolved base stations eNBs receive downloading of data and transmits thedownloaded data to the UE 101.

The E-UTRAN 102 includes a source base station and a target basestation. The source base station indicates a base station currentlybeing accessed by the UE 101. The target base station indicates a basestation that the UE 101 wants to access through hand-over. Namely, upona handover from the source base station to the target base station, theUE 101 terminates access to the source base station, and initiatesaccess to the target base station. In other words, when the UE 101accesses the source base station, the source base station downloadssource data. Upon the hand-over from the source base station to thetarget base station, the source base station forwards source data to thetarget base station. Further, the target base station downloads targetdata followed by the source data. At this time, the source base stationtransmits UE history information recorded as a UE Context to the targetbase station at the time of the handover.

The MME 103 accesses the E-UTRAN 102 by a wired channel. In this case,the MME 103 is connected to the E-UTRAN 102 through an SI interface. TheMME 103 executes a paging message distribution function to the evolvedbase station, a ciphering and integrity protection function ofNon-Access Stratum (NAS) signaling, an idle state mobility controlfunction, and a bearer control function.

The SGW 104 accesses the E-UTRAN 102 and the MME 103 by a wired channel.In this case, the SGW 104 is connected to the E-UTRAN 102 through an SIinterface. The SGW 104 can be provided with plurality of SGWs. Namely,the SGW 104 accesses at least one evolved base station. Further, the SGW104 executes a mobility control function of the UE 101 and the like.

The PGW 105 accesses the SGW 104 by a wired channel. The POW 105 furtheraccesses an IP network. The PGW 105 executes an IP address allocationfunction and a data filtering function for the UE 101. That is, the POW105 transmits data provided from an IP network 106 to the UE 101 throughthe SGW 104 and the E-UTRAN 102.

FIG. 2 is a sequence diagram illustrating a method for transmitting UEhistory information from a source base station to a target base stationat the time of a handover between macro base stations according to anembodiment of the present invention.

Referring to FIG. 2, a User Equipment (UE) 201 detects a signal of atarget base station (eNB) 203, and transmits a measurement report to aserving base station (eNB) 202 in step 205. Next, the serving basestation 202 analyzes the received measurement report, checks which basestation is a target base station of the UE 201, and decides a handoverof the UE based on a Tracking Area ID (TAI) and a used frequency band ofthe target base station 203 in step 206. The serving base station 202transfers a handover request message and UE history information to thetarget base station 202 in step 207. The target base station 203transmits a response indicating a handover request ACK to the servingbase station 202 in step 208. Then, the serving base station 202instructs the UE 201 to perform a handover to the target base station203 in step 209.

Subsequently, the UE 201 performs a handover to the target base station203 in step 210. The target base station 203 informs in step 211 an MME204 that the handover of the UE 201 is performed. The MME 204 transmitsa response signal (e.g. Path switch ACK) to the target base station 203in step 212, and instructs the service base station 202 to erase all UEinformation in step 213. The serving base station 202 informs thesuccess of reception of the UE information and the resources used by theUE 201 to the MME 204 in step 214.

The UE history information in step 207 contains cell ID, cell type(large, small, etc.), a served time from a corresponding base station,and information on a plurality of base stations with recent informationof a serving base station. The UE, history information is used toprevent a ping-pong handover of a UE from a target cell, namely, acontinuous handover of the UE between two base stations within a shorttime, and for a radio resource allocation algorithm to the UE afterestimation of a moving speed of the UE.

The following is an explanation of a method for using historyinformation of a UE operating in an idle mode according to an embodimentof the present invention. Herein, the idle mode is a state in which aRadio Resource Control (RRC) connection established between a UE and abase station is released. Meanwhile, an active mode means a state inwhich RRC connection between a UE and a base station is established.

FIG. 3 is a diagram illustrating history information recorded by a UEoperating in an idle mode according to an embodiment of the presentinvention.

Referring to FIG. 3, when a recording event occurs in an idle mode, a UEdirectly records information about the occurred recording event in idlemode UE history information. Upon conversion to an active mode, namely,upon setting the RRC connection between the UE and a base station, theUE transmits the recorded UE history information to the connected basestation.

In particular, as shown in FIG. 3, the UE operating in the idle modemanages the UE history information in a form of a table. The UE historyinformation contains at least one of an occurrence event, an ID andrelated information thereof selected by the user equipment, Public LandMobile Network (PLMN) information selected by the UE, a time influencedby each event, a time occupying a corresponding cell, and measuringinformation in the idle mode UE history information. Although not shown,besides the items listed, measurement information items with a cellsignal strength may be included in the table of FIG. 3. Here, the cellsignal strength may include a self-cell signal strength, a neighbor cellsignal strength, or a signal strength of currently camped frequency ordifferent band frequencies. As described above, it should be consideredthat respective items are listed in the table shown in FIG. 3 by way ofexample only. The respective items can be removed as needed. In anothercase, different items can be included in history information recorded ina UE operating in an idle mode.

FIG. 4 is a diagram illustrating a procedure of recording UE historyinformation by a UE operating in an idle mode according to an embodimentof the present invention.

Referring to FIG. 4, a UE 401 operating in an active mode converts to anidle mode in a first cell 404, moves to cell 04 407 in an idle mode, andagain operates in the active mode in a fourth cell 407.

In detail, when an event 408 converting to an idle mode occurs in thefirst cell 404, the UE 401 records information regarding the occurredevent 408 in idle mode UE history information. More particularly, anevent with a change of a serving cell occurs in the UE, and the UErecords a time stayed in a previous serving cell, namely, the first cell404, and information about a second cell 405 being a current servingcell in the idle mode UE history information.

Next, when the UE enters into an impossible service zone (i.e. an areawhere no service is available) and a service impossibility event 410occurs, the UE records a time stayed in a second cell 405 being aprevious serving cell and current service impossibility information inthe idle mode UE history information. When the UE enters into a thirdcell 406, it executes an event selecting a PLMN and a cell, and recordsthe occurrence time of the service impossibility event and informationabout a current PLMN and service cell in the idle mode UE historyinformation.

When the UE continuously moves and an event in which a serving cellchanges from the third cell 460 to the fourth cell 407 occurs, the UErecords a time stayed in the third cell 360 being a previous servingcell and information about the fourth cell 407 being a current servingcell in the idle mode UE history information.

When the UE accesses the fourth cell 407 and a conversion event from anidle mode to an active mode occurs, the UE records a time of the fourthcell 407 being a current serving cell operating in the idle mode in theidle mode UE history information. The idle mode UE history informationrecorded according to an embodiment of FIG. 4 is as shown in FIG. 3.

FIG. 5 is a sequence diagram illustrating a procedure of transmittingidle mode UE history information to a base station by a UE in an idlemode according to an embodiment of the present invention.

Referring to FIG. 5, after a connection between a UE 501 in an idle modeand an RRC is established, i.e. when the UE 501 is converted to anactive mode, in step 504, the UE 501 transmits idle mode UE historyinformation to a base station 503 in step 506. In this case, step 506can be performed by a request from the base station 502 in step 505 orindependently while omitting step 505.

Further, step 506 can be performed after step 504 or as a part of step504. The base station 502 which received the idle mode UE historyinformation may share the idle mode UE history information orinformation related thereto with another core network entity, i.e., acore network entity such an O & M server or an MME in step 507.Meanwhile, the base station 503 may share the idle mode UE historyinformation or information related thereto with another base stationneighboring therewith. Another base station or another core networkentity may estimate a moving speed of a UE and then use the idle mode UEhistory information in a radio resource allocation algorithm, inacquisition of information about its neighbor cells, PCI selectionalgorithm, problem discovery at the time of an enterpriser's cellplanning or setting a cell parameter, a coverage problem discovery of anenterpriser cellular network, and automatic setting of other networks.

FIG. 6 is a flow chart illustrating an operation of a UE according to anembodiment of the present invention.

Referring to FIG. 6, a UE determines if it is in an idle mode in step601. When the UE is in the idle mode, the UE executes Radio Frequency(RF) channel search in step 602. The UE determines if an idle mode eventto be recorded occurs in step 603. When the idle mode event to berecorded occurs, the UE further records relation event information inthe idle mode UE history information in step 604.

When the UE is not in an idle mode at step 601, the UE determines if itis attempting to access a base station in step 605. When the UE isattempting to access a base station, the UE determines if it succeeds inaccessing the base station to be converted to an active mode in step606. When the UE is converted to the active mode, the UE receives arequest for the idle mode UE history information from the base stationin step 607 and transmits the idle mode UE history information to thebase station in step 608. In this case, step 608 may be performedaccording to the request for the idle mode UE history information fromthe base station 520 in step 607 or be performed independently whileomitting step 607.

FIG. 7 is a block diagram illustrating an internal configuration of a UEaccording to an embodiment of the present invention. Referring to FIG.7, the UE according to an embodiment of the present invention includesan RF communication unit 710, a storage unit 720, and a controller 730.The storage unit 720 may include a UE history information storing area720A. The controller 730 may include a UE history information generator730A and a UE history information transmitting controller 730B.

The RF communication unit 710 performs transmitting and receivingfunctions of corresponding data for a wireless communication of the UE.The RF communication unit 710 may be composed of an RF transmitter thatup-converts a frequency of a signal to be transmitted and amplifies thesignal, and an RF receiver that low-noise amplifies a received signaland down-converts a frequency of the amplified signal. The RFcommunication unit 710 may receive data through a wireless channel,output the received data to the controller 730, and transmit data outputfrom the controller 730 through the wireless channel. In particular, theRF communication unit 710 according to an embodiment of the presentinvention may transmit the idle mode UE history information generatedfrom the UE in an idle mode to a base station.

The storage unit 720 stores programs and data necessary for the overalloperation of the UE according to an embodiment of the present invention,and may include a UE history information storing area 720A. The UEhistory information storing area 720A stores idle mode UE historyinformation generated in the UE in an idle mode.

The controller 730 controls signal transmission between respectiveblocks of another UE according to an embodiment of the presentinvention. In particular, the controller 730 controls a series ofprocedures for transmitting the idle mode UE history informationaccording to an embodiment of the present invention. To do this, thecontroller 730 may include a UE history information generator 730A andthe UE history information transmitting controller 730B.

The UE history information generator 730A determines if a UE is in anidle mode. When the UE is in the idle mode, the UE history informationgenerator 730A performs RF channel search to determine if a recordingevent to be recorded in UE history information occurs. Referring to FIG.4, the recording event may include at least one of an idle modeconversion event, a cell change event, an impossible service event, acell re-selection event, and a cell change event.

When the recording event occurs, the UE history information generator730A records relation information in the idle mode UE historyinformation. As described above, the idle mode UE history informationcontains at least one of an occurrence event, an ID and relatedinformation thereof selected by the UE, Public Land Mobile Network(PLMN) information selected by the UE, a time influenced by each event,a time camped in a corresponding cell, a cell signal strength, andmeasuring information. The UE history information transmittingcontroller 730B controls the generated idle mode UE history informationto be stored in the UE history information storing area 720B.

The UE history information transmitting controller 730B determines if aUE operating in an idle mode succeeds accessing a base station to beconverted into an active mode. When being converted to the active modefrom the idle mode, the UE history information transmitting controller730B controls the idle mode UE history information to be transmitted tothe base station. In this case, the idle mode UE history information canbe transmitted simultaneously with the accessing of the base station oraccording to a request from the base station.

In the method for managing UE history information according to thepresent invention, a UE may transmit its UE history information to aserving base station, and the serving base station may provide anefficient data transmission environment to the UE base on the UE historyinformation.

Although exemplary embodiments of the present invention have beendescribed in detail hereinabove, it should be clearly understood thatmany variations and modifications of the basic inventive concepts hereintaught which may appear to those skilled in the present t will stillfall within the spirit and scope of the present invention, as defined inthe appended claims.

What is claimed is:
 1. A method by a terminal, the method comprising:generating mobility history information upon entering an evolveduniversal mobile telecommunications system (UMTS) radio access network(E-UTRAN) from another radio access technology (RAT), the mobilityhistory information including information on a time duration for whichthe terminal stayed outside of the E-UTRAN; receiving, from a basestation, a request for the mobility history information; andtransmitting the mobility history information on to the base station, inresponse to the request.